Electrical ignition assembly for liquid fuel burners



Jan. 3, 1961 J. BREESE ETAL 2,966,942

ELECTRICAL IGNITION ASSEMBLY FOR LIQUID FUEL BURNERS Filed Nov. 4, 1955 ELECTRICAL IGNITION ASSEMBLY FOR LIQUID FUEL BURNERS James L. Breese and Milton D. Huston, Santa Fe, N. Mex., assignors, by mesne assignments, to Controls Company of America, Schiller Park, 111., a corporation of Delaware Filed Nov. 4, 1955, Ser. No. 544,918

5 Claims. (Cl. 158-91) This invention is directed to a new and improved method and mechanism for igniting the fuel in oil burners.

One purpose of the present invention is to provide an improved method of ignition for oil burner pots wherein the possibility of explosions during the ignition period is materially lessened.

Another purpose is to provide a heat storage means for initially vaporizing a substantial volume of liquid hydrocarbon fuel at the starting stage.

Yet another purpose is to provide means for bringing an oil burner to a high fire condition with a minimum time lag after ignition.

Another purpose is the provision of an improved electrical ignition assembly for oil burners wherein a flame spreads rapidly and evenly throughout the pot upon ignition.

Another purpose is the provision of an improved supporting arrangement of a burner pot and electrical ignition assembly.

Other objects will appear from time to time in the course of the ensuing specification and claims.

Referring generally now to the drawings:

Figure 1 is an assembly view in section illustrating the improved ignition assembly in its supported position in a burner pot; and

Figure 2 is a sectional illustration of a modified form of the invention.

Like elements are designated by like characters throughout the specification and drawings.

In Figure l the burner pot is designated at 50 and is provided with rows or levels of air inlet apertures 51. A support 52 is joined to the pot wall and is inclined to the wall of the pot as well as the bottom of the pot. An ignitor tube 53 is removably inserted in the support 52. The ignitor tube is provided with a shield 54 at its upper end portion' Electrically conductive poles 55 and 56 with terminals at their outer ends extend through the shield and terminate adjacent the lower end of the tube. A resistance heating element 57 is connected to these two poles at their lower ends. The resistance heating element may be formed of Nichrome wire or other equivalent material. A metallic wick 58 which may be formed of several superimposed layers of stainless steel screen wire may be supported at the lower end of the tube. The wick 58 is positioned closely adjacent the sump 58a in the bottom Wallof the burner pot. The sump 58a may create some paddling of fuel adjacent the wick 58.

The shield 54- is provided with indentations 59 that make a snug fit with the exterior of the support 53. An end plate 59a is joined to the tube 53 and overlies the upper end of tube 53. End plate 59a is spaced from the shield 54 as by indentations 59b. Apertures 59c are formed in the end plate so as to allow primary air for combustion to flow through the spaces between indentations 59, thence through the spaces between indentations 59b and down to the area adjacent heating element 57. A fuel inlet is designated at 60'. It supplies fuel through nited States Patent 0 i 2,966,942 Patented Jan. 3, 1961 a spray nozzle 60 which is located at approximately the mid-point of the support 52. Oil sprayed through the nozzle 60 may pass downwardly through the space be tween the support 52 and tube 53.

The form of the invention illustrated in Figure 2 is closely similar to that illustrated in Figure 1 with the following essential differences. In this form of the invention, the ignition tube or housing terminates at its lower end, at a point generally aligned with the spray nozzle 60. The. wick 61 is fixed to the lower end of the tube 62 and surrounds the resistance heating element 63. The lower portion of the wick is beneath the heating element. In this form of the invention oil sprayed from the nozzle 66} comes in contact with the metallic wick 61 Where it is vaporized for combustion.

Whereas we have shown and described an operative form of our invention we wish it to be understood that there are many modifications of this invention which will fall within the scope and spirit of the invention and which will be apparent to those skilled in the art. The drawings and description of the invention should be taken in a diagrammatic or illustrative sense and the scope of the invention should be limited only by the scope of the hereinafter appended claims.

The use and operation of our invention is as follows:

In both forms of the invention we position an ignitor tube or housing at an angle to the horizontal. This angle is on the order of 45. This particular disposition of the ignitor tube facilitates the location of the electrical leads at a point remote from the pot thus avoiding damage to the leads due to the heat in the pot. In both forms of the invention, the upper end of the support or housing for the electrically conductive poles terminates at a level above the lowermost level of air inlet apertures in the pot. Thus if any flooding of the pot occurs fuel will spill out through the primary air apertures rather than through the ignition tube. A metallic wick provides capillary passages for fuel vapors at a point adjacent the resistance heating element and in each form of the invention these passages surround an opening opposed to the heating element.

In both forms of electrical ignition assembly the hydrocarbon fuel is initially heated and gasified by electrical energy. When current is supplied to the resistance heating element the metallic wick will be heated to a sufficient temperature in relation to the volume of fuel involved, so that when fuel begins to flow, and the wick fills with liquid fuel, the stored heat in the wick is itself sufficient to vaporize at least the initial increment of fuel to the wick. This vapor forms about the resistance heating element, and also, in the space immediately exterior to the Wick. In effect, the wick and the adjacent portions of its support members incuding the housing and wick support tube form a heat storage reservoir.

Means are provided for circulating air through the area of the combustion chamber adjacent the heating element. In the forms of the invention illustrated in Figures 1 and 2, air external to the burner pot is supplied through the ignition tube to the combustion chamber surrounding the heating elements. Secondary air is supplied to the area surrounding the wick. This flow of air in all cases is insufiicient to cool the heating element, when energized, below the ignition temperature of the fuel. The flow of air is sufficient, however, to initiate primary combustion.

As the vapor due to the stored heat in the wick forms, or almost immediately after it begins to form, the vapor in the housing within the tube and inside of the wick is ignited by the resistance and explodes out through the housing. This initial flame is directed downwardly toward the bottom of the pot and at a point relatively close to the pot side wall. At the same time, or instantaneously thereafter, the vapor in the space exterior to the wick is ignited and the end result is a substantial combustion of vaporized fuel which is effective to initiate further vaporization and consequent combustion, the ignition of the pot being thus started. Thus the flame will spread rapidly and evenly over the surface of oil covering the pot bottom.

In each form of the invention the ignition tube is simply inserted through the pot wall and may be removed for inspection and repair if necessary. The ignition tube may be removed by a simple rectilinear upward and outward pull. In both Figures 1 and 2, the upper opening in the support is well above the lowermost row of air inlet apertures and fuel spillage due to flooding of the pot will occur through the lowermost row of apertures rather than through the support.

We claim:

1. A burner pot and ignition assembly including a vaporizing burner pot for liquid fuels, said pot having vertically spaced rows of apertures formed in'the side wall thereof for the admission of primary and secondary air to the interior of the pot, the side wall of the pot having an opening formed therein, and an insertable and removable electric ignition assembly aligned with said opening along an axis inclined to the side wall of the pot, and to the bottom of the pot, said assembly including a generally cylindrical support positionable with its axis along said axis, and a generally cylindrical screen wick carried by the end of said support, a resistance heating element positioned in the interior of said Wick, and a nozzle positioned adjacent said wick and adapted to deliver a stream of fuel against the exterior of said wick.

2. The structure of claim 1 characterized by and including means for delivering air through the interior of said support and through the interior of said wick in a direction toward the bottom of the burner pot.

3. The structure of claim 1 wherein said support is positionable generally coaxially with and in the interior of a generally cylindrical tube fixed to the side wall of the pot and inclined thereto, and said wick and nozzle are located at a position in said tube outwardly and away from the bottom of said burner pot.

4. A vaporizing liquid fuel burner pot constructed and arranged to provide a heat storage reservoir whereby ignition of the fuel may occur substantially directly upon energization of a resistance heating element, said pot including, in combination, a generally circumferential side wall and bottom, said side wall having a plurality of air admission apertures located therein intermediate the top and bottom of the pot, and an opening for an ignition assembly adjacent the pot bottom, a sleeve in communication with the opening and having its axis inclined to the side wall of the pot and the bottom of the pot, and an electrical ignition assembly forming a heat storage reservoir insertable and removable in the sleeve in a direction generally parallel to the longitudinal axis of the sleeve, said ignition assembly including a generally cylindrical support, the upper end of said support terminating exteriorly of the said wall, and a generally cylindrical wick carried by the lower end of the support, said wick and at least that portion of the support adjacent the wick being of a metallic material capable of storing heat to thereby provide a stand by heat storage reservoir, said sleeve surrounding and being spaced from the heat storage reservoir so as to protect said heat storage reservoir against loss of heat, a resistance heating element generally axially aligned with said wick and generally adjacent thereto, means for directing a flow of air downwardly toward the heating element, said wick being positioned in the direct path of airflow downwardly within said support so that a flame produced upon ignition of heated vapor in the vicinity of the wick will be projected downwardly into the pot, and means for delivering fuel to the wick and adjacent supporting portion of the cylindrical support to thereby provide a source of fuel vapor to the heat storage reservoir.

5. A vaporizing liquid fuel burner pot constructed and arranged to provide a heat storage reservoir whereby ignition of the fuel may occur substantially directly upon energization of a resistance heating element, said pot including, in combination, a generally circumferential side wall and bottom, said side wall having a plurality of air admission apertures located therein intermediate the top and bottom of the pot, and an opening for an ignition assembly adjacent the pot bottom, a sleeve in communication with the opening and having its axis inclined to the side wall of the pot and the bottom of the pot, and an electrical ignition assembly, at least the bottom portions of which forms a heat storage reservior insertable and removable in the sleeve in a direction generally parallel to the longitudinal axis of the sleeve, said ignition assembly including a generally cylindrical support, the upper end of said support terminating exteriorly of the said wall, and a generally cylindrical wick carried by the lower end of the support, said wick and at least that portion of the support adjacent the wick being of a metallic material capable of storing to thereby provide a stand by heat storage reservoir, said sleeve surrounding and being spaced from the heat storage reservoir so as to protect said heat storage reservoir against loss of heat, a resistance heating element generally axially aligned with said wick and generally adjacent thereto, means for directing a flow of air downwardly toward the heating element, said wick being positioned in the direct path of air flow downwardly within said support so that a flame produced upon ignition of heated vapor in the vicinity of the wick will be projected downwardly into the pot, and means for delivering fuel to the wick and adjacent supporting portion of the cylindrical support to thereby provide a source of fuel vapor to the heat storage reservoir.

References Cited in the file of this patent UNITED STATES PATENTS 1,903,364 Grant Apr. 4, 1933 2,229,717 Brace et a1. Jan. 28, 1941 2,309,319 Johnston Ian. 26, 1943 2,438,823 Resek et al Mar. 30, 1948 2,509,399 Resek May 30, 1950 2,540,594 Price Feb. 6, 1951 2,553,975 Little May 22, 1951 2,646,111 Long Jan. 21, 1953 2,712,352 Manor et al. July 5, 1955 2,713,388 Todorofi July 19, 1955 2,729,282 Lennox Jan. 3, 1956 2,756,811 Little Jan. 31, 1956 2,779,398 Brown Jan. 29, 1957 FOREIGN PATENTS 477,076 Canada Sept. 18, 1951 lama-t. 

